Start building out type inference.

build.rs

@@ -68,7 +68,10 @@ fn generate_tests(f: &mut File, path_so_far: PathBuf) -> std::io::Result<()> {
                     "  assert_eq!(errors.len(), 0, \"file should have no validation errors\");"
                 )?;
                 writeln!(f, "  let syntax_result = syntax.eval();")?;
-                writeln!(f, "  let ir = IR::from(syntax);")?;
+                writeln!(
+                    f,
+                    "  let ir = syntax.type_infer().expect(\"example is typed correctly\");"
+                )?;
                 writeln!(
                     f,
                     "  assert_eq!(syntax_result, ir.eval(), \"syntax equivalent to IR\");"